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Montana Field Guides

Western Harvest Mouse - Reithrodontomys megalotis

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Global Rank: G5
State Rank: S4

Agency Status
USFWS:
USFS:
BLM:
FWP Conservation Tier: 3


 

External Links





 
General Description
The relatively small Western Harvest Mouse averages 5 1/2 inches long and less than 1/2 ounce in weight. Its scaly tail comprises more than half of its length. The upper fur and tail color appears grayish brown, with a darker midline and buffy sides. Below, tail and body are white or grayish. Along with the nearly hairless bicolored tail, large ears and a groove running down the front of each incisor help differentiate the Western Harvest Mouse from similar mammals.

Diagnostic Characteristics
See Hoofer et al. (1999) for information on discrimination between R. megalotis and R. montanus using cranial characters.

Species Range
Montana Range

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Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 188

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Records associated with a range of dates are excluded from time charts)



Migration
Non-migratory.

Habitat
Dense grassy areas, sage-grassland.

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Granivorous, also consumes some herbaceous materials and insects.

Ecology
Tolerant of conspecifics.

Reproductive Characteristics
Average 4.0 young/litter (n=2). In warmer parts of range breeds year round. Probably March to October in MT. Females are sexually mature in 4 months, polyestrous, several litters year.

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • Allen, K.L., T. Weaver, and D. Flath. 1994. Small mammals in Northern Rocky Mountain ecosystems. Unpubl. report to Bureau of Land Management and United States Forest Service, August 31, 1994. Montana State Univ., Bozeman. 54pp.
    • Bauer, Delane, 2002, 2002 Four Seasons Wildlife Study. Savage Mine Report, Richland County, Montana.
    • Clark, B. K. and D. W. Kaufman. 1990. Short-term responses of small mammals to experimental fire in tallgrass prairie. Can. J. Zool. 68:2450-2454.
    • Clark, B. K., et al. 1988. Long-distance movements by Reithrodontomys megalotis [sic] in tallgrass prairie. Am. Midl. Nat. 120:276-281
    • Clark, T. W. and M. R. Stromberg. 1987. Mammals in Wyoming. University of Kansas Museum of Natural History, Public Education Series Number 10. xii + 314 p.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1975, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1975. Proj. 71-23-A. December 31, 1975.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1979, Annual wildllife report of the Colstrip Area for 1978. Proj. 195-85-A. April 6, 1979.
    • Econ, Inc., Helena, MT., 1978, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife and wildlife habitat monitoring study. Proj. 190-85-A. December 31, 1978.
    • Econ, Inc., Helena, MT., 1988, Wildlife monitoring report, 1987 field season, Big Sky Mine. March 1988. In Peabody Mining and Reclamation Plan Big Sky Mine Area B. Vol. 8, cont., Tab 10 - Wildlife Resources. Appendix 10-1, 1987 Annual Wildlife Report.
    • Fjell, Alan K., 1986, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1985 field season. March 1986.
    • Fjell, Alan K., and Brian R. Mahan, compilers., 1984, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1983 field season. February 1984.
    • Fjell, Alan K., and Brian R. Mahan., 1985, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1984 field season. February 1985.
    • Fjell, Alan K., and Brian R. Mahan., 1987, Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1986 field season. April 1987.
    • Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
    • Geppert, T. J. 1984. Small mammals of the Shield Trap, East Pryor Mountain, Montana. M.S. thesis. University of Iowa, Iowa City. 45 pp.
    • Heske, E. J., R. S. Ostfeld and W. Z. Lidicker, Jr. 1984. Competitive interactions between Microtus californicus and Reithrodontomys megalotis during two peaks of Microtus abundance. J. Mammal. 65:271-280.
    • Hoffmann, R. S. and D. L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 p.
    • Hoffmann, R.S., P.L. Wright, and F.E. Newby. 1969. Distribution of some mammals in Montana. I. Mammals other than bats. Journal of Mammalogy 50(3): 579-604.
    • Jones, J. K., D. M. Armstrong, R. S. Hoffmann and C. Jones. 1983. Mammals of the northern Great Plains. University of Nebraska Press, Lincoln. 379 p.
    • Kaufman, G. A., D. W. Kaufman and E. J. Finck. 1988. Influence of fire and topography on habitat selection by PEROMYSCUS MANICULATUS and REITHRODONTOMYS MEGALOTIS in ungrazed tallgrass prairie. J. Mammal. 69:342-352.
    • Kritzman, Ellen B. 1977. Little mammals of the Pacific Northwest. Pacific Search Press, Seattle, WA.
    • Montana Dept. of State Lands, 1976, Draft environmental impact statement for proposed open cut mining contract for Amercan Colloid Company. November 12, 1976.
    • Pefaur, J. E. and R. S. Hoffmann. 1971. Merriam's shrew and hispid pocket mouse in Montana. American Midland Naturalist 86(1):247-248.
    • Powder River Eagle Studies, Inc., Gillette, WY., 1994?, Big Sky Mine 1993 wildlife studies. Date???
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Schladweiler, Philip, and John P. Weigand., 1983, Relationships of endrin and other chlorinated hydrocarbon compounds to wildlife in Montana, 1981-1982. September 1983.
    • Waage, Bruce C., 1993, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Monitoring Report; 1992 Field Season. December 1993.
    • Waage, Bruce C., 1995, Western Energy Company Rosebud Mine, Colstrip, Montana:1994 Annual Wildlife Monitoring Report; December 1, 1993 - November 30, 1994. February 27, 1995.
    • Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
    • Waage, Bruce C., 1999, Western Energy Company Rosebud Mine, Colstrip, Montana: 1998 Annual Wildlife Monitoring Report; December 1, 1997 - November 30, 1998 Survey Period. February 24, 1999.
    • Waage, Bruce C., compiler., 1984, Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1983 Field Season. June 1984.
    • Waage, Bruce C., compiler., 1986, Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1985 Field Season. December 1986.
    • Webster, W.D. and J.K. Jones. 1982. Reithrodontomys megalotis. Mamm. Species No. 167. 5 pp.
    • Western Energy Co., Colstrip, MT. Unpub., 1983, Western Energy Company's Application for Amendment to Surface Mining Permit NO. 8003, Area B: sections 7, 8, 17,18 T1N R41E, sections 12, 13 T1N R40E, Mining Expansion. March 1983.
    • Western Energy Co., Colstrip, MT., 1980, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Report, 1980.
    • Western Energy Co., Colstrip, MT., 1981, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Report, 1981.
    • Western Energy Co., Colstrip, MT., 1981, Western Energy Company's Application for a Surface Mining Permit: Area C - Block 1. Vol. 1. May 1981.
    • Western Technology and Engineering, Inc. (WESTECH)., 1996, Wildlife Monitoring Absaloka Mine Area Annual Report, 1995. Montana SMP 85005. OSMP Montana 0007D. Febr. 23, 1996.
    • Western Technology and Engineering, Inc. (WESTECH)., 1997, Wildlife Monitoring Absaloka Mine Area Annual Report, 1996. Montana SMP 85005. OSMP Montana 0007D. Mar. 1997.
    • Western Technology and Engineering, Inc. (WESTECH)., 1999, Wildlife Monitoring Absaloka Mine Area Annual Report, 1998. SMP 85005. OSMP Montana 0007E. April 1999.
    • Westmoreland Resources, Inc., Hardin, MT., 1981, Upper Sarpy Basin Wildlife Study. In 1981 Wildlife Report. April 1982.
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Citation for data on this website:
Western Harvest Mouse — Reithrodontomys megalotis.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on October 25, 2014, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=AMAFF02030
 
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